In order to measure a potential on a body surface of a patient by using an electrocardiograph, a number of terminals stretching from the substrate of a measurement apparatus generally need to contact the body surface of the patient. The body surface of the patient is unlevel in different manners between patients. When the terminal and the substrate are connected to each other through a usual lead, since a distance therebetween may not be changed according to a shape of the body surface of the patient, it has been difficult to connect a number of terminals to the body surface of the patient. Also, there has been a risk that a connecting part between the terminal and the lead or between the lead and the substrate is disconnected while in use.
As such, Patent Document 1, for example, suggests a technique to connect the terminal and the substrate by using a compression spring. According to this technique, by compressing the compression spring when the terminal is pressed against the body surface of the patient, the distance between the terminal and the substrate is changed, thereby facilitating contact of a number of terminals to the body surface of the patient.